The present disclosure relates to a water injection device of an internal combustion engine as well as such an internal combustion engine. A further aspect of the disclosure relates to a method for operating such a water injection device.
As a result of increasing demands in terms of reduced carbon dioxide emissions, internal combustion engines are increasingly being optimized in terms of fuel consumption. However, known internal combustion engines cannot be operated optimally in terms of consumption at operating points with high load since operation is restricted by knocking and high exhaust gas temperatures. One possible measure to reduce knocking and lower the exhaust gas temperatures is the injection of water. In this case, separate water injection systems are normally present in order to enable the injection of water. A water injection system for an internal combustion engine with exhaust gas recirculation is known e.g. from WO 2014/080266 A1 in the case of which the water is injected into the mass flow of the exhaust gas recirculation.
The pump used to convey water is switched off between the operating points at which the water injection system is activated. This means that the water is located in the injectors and the lines of the water injection system. As a result of the high temperatures of the parts of the internal combustion engine in the vicinity of the water injection system, the stationary water can heat up and possibly evaporate. This effect is amplified in the case of journeys at a great height where the air pressure is lower. As a result of the formation of steam, functional impairments can arise when restarting the water injection system since the system pressure can only be built up with a delay as a result of the steam. The water injection system is thus ready for operation with a delay. As a result of this delayed readiness for operation, temperature peaks in the exhaust gas and knocking events in combustion can occur in the case of rapid jumps in load.